Pressure-measuring instrument



L. W.- THDMPSQN Filed Nov. 1, 197:1?

PRESSURE MEASURING INSTRUMENT [IVE iii

p WW m W m pyupnp u i a tit l, i lull] i w llul l a slut ha r l l llhe Plffiu measurin instruments antl W ta for use in any instance tvl he measuretl, it is more par use as a pressure-inseam in l'lUW meter :lor measuringthe tlovv or through pipes. rtccortlingly l have cally illustrated anti tlescriherl my invention as ernhorlierl in a how meter. it is to he untlerstoorh hovvever, that this is only hy ivau' oi example ancl that the invention is not lim itetl to this application.

The invention relates especially to such instruments oi What may he termetl the electric transformer type, this lacing the type eli closed in the patent to Jacoh "t ll. late lair-y aml myself, l lo prisoner, patented llov. ll], i925. .rln instrument oi such type is in the nature an electrical transformer wherein the primary comprises a vvincling; associated With. the trailing leg oi the ll-tuhe anrl the secondary comprises liquich such as mercury Which is a conrluctor ol electricity antl Which in risinp; in the trailing leg at thell-tuhe proviclcs an annular ring or loop oi liquicl surroimtlmp the primary vvinrling. 'lhe licyuicl ring or loop terms a closed seconilary having; a single turn which varies in cross section. as the lictuicl rises ancl hills in the trailing oi the lltnhe. it measuring circuit incluclin source at alternatiru. potential is connectetl to the primary ninrl ing ancl there is createcl in such circuit a how oil? current which "varies rlirectly With. the or use sectional area oi the liquicl ring Which in turn is a function of its height. This current then measureol to give a measure of the'tluicl hlovv and may he integrated to give the total :lilorv,

. "With an instrument of this type, the mer carry in the ll-tuhe is actecl on directly by the pressure or pressure difference to he measurecl until this heing; the case, consiclerahle change in pressure rlilierence is requiretl to elicct sutlicient cletlection of the mercury in the ll-tuhe to renrler the instrument practicahl'c lhe instrument therefore, isnot vvell arlaptecl tor measuring small pressures or small pressure tliherences.

lhe ohject oi. my present invention is to provide an improved pressursmeasuring; in strument oi the type referred to which is aclaptecl for measuring" accurately relatively small changes in pressure or pressure (litter--- 'n s ancl tor a consideration oi What it he to he novel suit my invention, attention l lllllll .lllll up ma a up i i ltl i all at u lloiv meter tinho 'ly 1W m it is ll ip' in on line ll in i the rl rection oi the arrows.

l .tlccortlin to my preterit inventioin l pro title a tra rmer structure comprisi a "Winrline' W terms the primary o transloimer ancl litpiitl loop Which. terms the secontlary oi the transtormeru, an intlici inn circuit hein connects cl to the transitormcr an primary. l'lorveyein, instearl oi raising; anrl lUWBIl'll he lirp. 'rl level to e changes in the rtustances out the lirpiicl loop, ll maintam the lltttlitl always at its manimurn level antl ll thenproviGe in. con ection With it a separat inn memher prelt .ahly in the harm oil a piece oi insulated materiah which is raisetl anrl lon ererl relatively to the lirtuirl loop to separate or split the saline. lhe s giarator mcmher is then movetl hy some suitahle means which is so responsive to changes in aressure orpressuro clitleronce ancl which is at as sensitive a nature as is clesirccl. lPi-eiferahly, l use a pressure or pressurealillei once responsive (levies oi an in vertetl hell type hecause with such a type comparatively large movement may he ohtainecl with a comparatively small change in pressure or pressure clitl'erence lieierring to the drawing, l inclicates a sealc'tl casing" which may he lormecl oi any suitable material; Connected. to the antlersirle oi the cover tor the casing is a hracliet 52; on which is supportecl the rectangular core 3 oil a transtormen such. core hemp; macle of laminations as usual in connection with transformer core construction. Fiurrounrlint; one lea oi the transtormer core is struc-- ture comprisinp Walls 4t anti 5 which ilelinc a continuous chsluloer ti arouncl such transformer leg. la the present instance continuous chamber 6 is rectangular. Ti lie Wtl-llS forming chamber 6 are supportecl hy rocls 'l' "which at their upper encls are connectecl to the top oil the transformer core. Surrouncling chamber 6 is a primary trausiormer Winrlinn; 8, the terminals oi which are connecterl hy learl Wires 9 to a source of alternating current 10, there lacing; incluclecl in the circuit suitahle measuring instruments it which may he instruments for integrating, inrlicatimg' and lllll.

llll

recording the flow of current in such circuit. In the drawing, the potential and current connections 11 and 11 and fuses 11 for the instruments are indicated.

It is to be understood that this illustration is only by way of example and that the in-' struments will be connected into the circuit is in the form of a rectangular plate and when it is raised and lowered in the chamber, it will be seen that it serves to separate or split the liquid loop, thus varying the electrical resistance of the liquid loop. To take care of the change in volume of liquid in chamber 6 when separatormember 14 moves, there is provided an overflow well 15 which :is

mounted on the side of wall 4 adjacent its upper end and is connected to chamber 6 by passages 16. Well 15 is of a size such that the amount of liquid displaced by member 14 effects only slightly the liquid level.

Connected to member 14 is a rod 17 carried insuitable upper and lower guides 18 and 19, such guides being. shown in the present instance as being in the form of spaced rollers. Mounted on rod 17 is an inverted annular bell float 20 which rides in a liquid 21 with which casing 1 is partially filled. Liquid 21 may be oil, for example. It .is to this bell floatthat the re ssure or pressure difference to be measured is applied. In the present instance, 22 indicates a conduit through which a fluid to be metered flows and 23 indicates a pressure-difierence-creating device therein, a

pressure-diflerence-creating device ofknown t pebeing illustrated, it being the type disclosed in the patent to Dodge, No. 1,298,471,

. granted Mareh25, 1919. The leading and trailing pipes 24 and 25 connect pressure difference-creating device to the inside and outside of bell float 20 in the usual manner.

The operation is as follows:

At zero or no flow through conduit 22, the

parts stand in the positions shown in Fig. 1,

the bell float 20-and the separator member 14 being in the lowermost positions. At this -'time the mercury loop which forms the seconda of the transformer is split almost entirely in two, it being complete only atits lowermost portion. There is a small flow of currentin the circuit 9, but instruments .11 are compensated to read zero with this small current flow. The mercury ring may be split entirely in two by member 14 but this is not done preferably because of the fact that a considerable movement of the member 14 in a mercury ring on account of the characteristics of the device at low flow.

When flow of fluid takes place through conduit 22, the leading and trailing pressures set up by the pressure-difference-creating device are applied, to bell float 20, the float being raised in accordance with the pressure difference created. As the float is raised it lifts separator member 14 thereby decreasing the amount the mercury loop is split (in other words, increasing the effective height of the mercury loop). This effects an increase in flow of current in the primary circuit of the transformer, such increase in flow of current being measured by the instruments 11. As flow of fluid through conduit 22 increases and decreases, float 20 will be raised and lowered, thereby raising and lowering separator member'14 and increasing and decreasing the flow of current in the primary circuit. The flow of current thus serves as a measure of the diiferential resure which in turn is a measure of the ow of fluid through conduit 22. Float 20 may be shaped and constructed to give the desired verticalmovem'ent for the change in pressure available for moving it, so that a comparatively large vertical movement may be obtained with a comparativel small change in pressure or pressure dif ference. In this connection, it will be noted that inverted bell float 20 is required to displace only a compsratively small quantity of mercury, this ing the quantity represented by the volume of separator member 14.

This means, therefore, that the-bell float is tances a and I) represent the effective depths of the chamber of the liquid loop. The sha 6, the effective depth of the liquid loop at zero flow and the external resistance of the primary circuit may be adjusted as found desirable or as required, to give the desired characteristic relation between the current flowing in the primary circuit and the quantity represented by the pressure diflerence to be measured.

By the above described arrangement, it

will be seen that Iavoid displacing all the liquid which forms the liquid loop of the transformer secondary, and instead displace only a small portion of it. This means that only a' small amount of force is required to effect. the changesin the effective resistance of the-liqpid loop. Then by utilizing a device whic in response to comparatively small 1:30

changes in pressure or pressure difference is capable of moving the separator through the desired travel, I thereby provide an arrange ment capable of measuring accurately coIn paratively small changes in pressure or pres sure di'l'lerence.

ln accordance with the provisions of the patent statutes, I have described the prin ciple of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but ll desire to have it understood that the appa ratus shown is only illustrative and that the invention may be carried 01% by other means.

What l claim as new and desire to secure by Letters Patent of the United States, is:

1. in a measuring device, walls defining a chamber in the form of a loop, a primary transformer winding associated with said chamber, a liquid in said chamber which is a conductor oi electricity and which forms a secondary transformer winding in the form of a liquid loop, an insulating means for dividing said liquid loop, means for moving said insulating means to vary the effective depth of said liquid loop, and a measuring circuit connected to said primary windin 2. In a measuring device comprising as a part of its structure means providing a liquid loop which is a conductor of electricity, a dc vice formed o'l insulating material which is moved in response tochanges in the value to be measured tor splitting the liquid loop axially to vary the effective cross-sectional area of the liquid loop.

3. ln a measuring device, a transformer core, a primary winding thereon adapted to have a measuring circuit connected to it, means providing a secondary winding :tor

the core in the form of a loop o'l conducting liquid, and a movable member formed of insulating material for splitting the liquid loop axially to vary the effective cross-sectional area of saidliquid loop.

1. In a measurin device, a transformer core, 'a primary win ing thereon adapted to have a measuring circuit connected to it, means providing a secondary winding for the core in the form ofa loop of conducting liquid, a separator formed of insulating ma terial movable relatively to the loop for splitting the liquid loop axiallv to vary the efiective cross-sectional area of said liquid loop, and means for positioning said separator in response to variations in the value of the quantity to be measured.

5. In a measuring device. a transformer core, a primary winding thereon adapted to have a measuring circuit connected to it,

.means providing a secondary winding on the core in the iorm oi a loop of conducting 'l1qu1d,'a se arator formed of insulating material mova le relatively to the loop for splitting the loop in anaxial direction to vary the eliective cross-sectional area of said liquid loop, and a pressure-responsive device for positioning said separator.

6. In a measuring device comprising as a part of its structure means providing a liquid loop which is a conductor of electricity, an' insulating device which is moved in response to changes in the value to he measured to split said liquid loop axially to a greater or lesser degree whereby its eii'ective, cross-sectional area is varied.

In witness whereof, I have hereunto set my hand this 31st day of Uctober, 1927.

T liUUlS W. THOMPSON.

ill 

